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What is sleep for?
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What is sleep for?
16/ 5/2008
Q
Sleeping takes up about a third of our lives. What is its purpose?
A Sleep researchers cannot really agree on this, but here are some theories:
Evolution
While sleeping, we can't eat or mate and leave ourselves vulnerable to attack.
So why do it when it offers little survival advantage?
People would argue animals who sleep the most are most protected as they don't attract attention from predators.
Mental well-being
Feeling irritable and slowed-up is common after a poor night's sleep.
I've seen many people with anxiety and depression list sleep problems as their worst symptom. But is it a precipitant or a consequence of mental illness?
Consolidating and improving memory
Studies demonstrate a 15 per cent improvement in memory after sleep; linked especially to REM sleep, commonly associated with dreaming.
However, certain antidepressants can eliminate this REM phase with no apparent deficits in memory.
Conservation of energy
Our bodies are like batteries that need to be recharged regularly. Many animals with higher metabolic rates need more sleep.
This theory would also explain why babies need more and older people need less. But the brain is very active during REM sleep, so this can't the whole answer.
Brain and body restoration
Slow wave and REM sleep are thought to repair and restore the effects of daytime cerebral `wear and tear'.
Growth hormone is produced and some studies implicate the immune system.
There have been recorded links between lack of sleep and obesity, diabetes, heart disease, and depression.
Dr Neel Halder is an experiences psychiatrist and a member of the Royal College of Psychiatry.
Got an opinion you want to share?Are you having to stay at home this summer holiday?
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